1. Field of the Invention
The present invention relates to a display device having a light emitting element.
2. Description of the Related Art
In recent years, development of a display device having a light emitting element typified by an EL (electroluminescence) element (in particular, an organic EL element) has been carried out. By utilizing benefits of high image quality, wide viewing angle, thin shape, lightweight, etc. due to self-light emitting type, widespread application of the display device having the light emitting element has been expected. The light emitting element includes a structure formed by laminating an anode, a light emitting layer and a cathode over a substrate. For example, when an anode is formed at the side of a substrate, a so-called bottom emission type display device, in which the anode is transparent and light generated from a light emitting layer is emitted toward the substrate, is known (see patent document 1).
[Patent Document] Japanese Patent Application Laid-Open No. 2003-248440
When light generated in a light emitting layer is emitted through a substrate, light passes through insulating films such as a planarizing film, an interlayer insulating film and a gate insulating film of a transistor so that the light is ultimately emitted to the outside of the substrate, as shown in the patent document 1. In this case, diffused reflection is caused due to slight-rough surfaces of the insulating films every time light passes through each insulating film, which varies a light emitting direction. Accordingly, an outline of a light emitting region corresponding to one pixel becomes indistinct since stray light is caused and light leakage is caused with respect to a non-light emitting region from the light emitting region corresponding to one pixel or characteristics of a transistor is deteriorated due to leakage of light into an active layer (a semiconductor layer) of the transistor, which results in problems.
Further, the above problems are caused in not only the bottom emission type light emitting display device, but also a so-called dual emission type display device, in which light is emitted through both a top and bottom faces of a light emitting layer.